This invention generally relates to ink jet printer apparatus and methods and more particularly relates to an ink jet printer with cleaning mechanism, and method of assembling same.
An ink jet printer produces images on a receiver by ejecting ink droplets onto the receiver in an imagewise fashion. The advantages of non-impact, low-noise, low energy use, and low cost operation in addition to the capability of the printer to print on plain paper are largely responsible for the wide acceptance of ink jet printers in the marketplace.
In this regard, xe2x80x9ccontinuousxe2x80x9d ink jet printers utilize electrostatic charging tunnels placed close to the point where ink droplets are being ejected in the form of a stream. Selected ones of the droplets are electrically charged by the charging tunnels. The charged droplets are deflected downstream by the presence of deflector plates that have a predetermined electric potential difference between them. A gutter may be used to intercept the charged droplets, while the uncharged droplets are free to strike the recording medium.
In the case of xe2x80x9con demandxe2x80x9d ink jet printers, at every orifice an actuator is used to produce the ink jet droplet. In this regard, either one of two types of actuators may be used. These two types of actuators are heat actuators and piezoelectric actuators. With respect to heat actuators, a heater placed at a convenient location heats the ink and a quantity of the ink will phase change into a gaseous steam bubble and raise the internal ink pressure sufficiently for an ink droplet to be expelled to the recording medium. With respect to piezoelectric actuators, a piezoelectric material is used, which piezoelectric material possess piezoelectric properties such that an electric field is produced when a mechanical stress is applied. The converse also holds true; that is, an applied electric field will produce a mechanical stress in the material. Some naturally occurring materials possessing these characteristics are quartz and tourmaline. The most commonly produced piezoelectric ceramics are lead zirconate titanate, lead metaniobate, lead titanate, and barium titanate.
Inks for high speed ink jet printers, whether of the xe2x80x9ccontinuousxe2x80x9d or xe2x80x9cpiezoelectricxe2x80x9d type, have a number of special characteristics. For example, the ink should incorporate a nondrying characteristic, so that drying of ink in the ink ejection chamber is hindered or slowed to such a state that by occasional spitting of ink droplets, the cavities and corresponding orifices are kept open. The addition of glycol facilitates free flow of ink through the ink jet chamber.
Of course, the ink jet print head is exposed to the environment where the ink jet printing occurs. Thus, the previously mentioned orifices are exposed to many kinds of air born particulates. Particulate debris may accumulate on surfaces formed around the orifices and may accumulate in the orifices and chambers themselves. That is, the ink may combine with such particulate debris to form an interference burr that blocks the orifice or that alters surface wetting to inhibit proper formation of the ink droplet. Also, the ink may simply dry-out and form hardened deposits on the print head surface and in the ink channels. The particulate debris and deposits should be cleaned from the surface and orifice to restore proper droplet formation. In the prior art, this cleaning is commonly accomplished by brushing, wiping, spraying, vacuum suction or spitting of ink through the orifice.
Thus, inks used in ink jet printers can be said to have the following problems: the inks tend to dry-out in and around the orifices resulting in clogging of the orifices; the wiping of the orifice plate causes wear on plate and wiper and the wiper itself produces particles that clog the orifice; cleaning cycles are time consuming and slow productivity of ink jet printers. Moreover, printing rate declines in large format printing where frequent cleaning cycles interrupt the printing of an image. Printing rate also declines in the case when a special printing pattern is initiated to compensate for plugged or badly performing orifices.
Ink jet print head cleaners are known. A wiping system for ink jet print heads is disclosed in U.S. Pat. No. 5,614,930 titled xe2x80x9cOrthogonal Rotary Wiping System For Inkjet Printheadsxe2x80x9d issued Mar. 25, 1997 in the name of William S. Osborne et al. This patent discloses a rotary service station that has a wiper supporting tumbler. The tumbler rotates to wipe the print head along a length of linearly aligned nozzles. In addition, a wiper scraping system scrapes the wipers to clean the wipers. However, Osborne et al. do not disclose use of an external solvent to assist cleaning and also do not disclose complete removal of the external solvent.
Therefore, there is a need to provide a suitable ink jet printer with cleaning mechanism, and method of assembling same, which cleaning mechanism is capable of simultaneously cleaning the print head surface and ink channels.
An object of the present invention is to provide an ink jet printer with cleaning mechanism and method of assembling same, which cleaning mechanism simultaneously cleans a surface of a print head belonging to the printer as the cleaning mechanism cleans ink channels formed in the print head.
With the above object in view, the invention resides in an ink jet printer, comprising a print head having a surface thereon and an ink channel therein; and a cleaning mechanism associated with said print head and adapted to simultaneously clean contaminant from the surface and the ink channel.
According to an exemplary embodiment of the invention, an ink jet printer comprises a print head having a surface thereon surrounding a plurality of ink ejection orifices. The orifices are in communication with respective ones of a plurality of ink channels formed in the print head. A vacuum hood capable of sealingly surrounding at least one of the orifices has a first passageway formed therethrough in communication with the orifice. The hood vacuums contaminant from the ink channels in communication with the orifice. A solvent delivering wiper is connected to the hood and has a second passageway formed therethrough alignable with the print head surface. The second passageway delivers a liquid solvent cleaning agent to the print head surface to flush contaminant from the surface. In this manner, contaminant residing on the surface is entrained in the solvent while the wiper flushes contaminant from the surface. A vacuum canopy is connected to the wiper and has a third passageway formed therethrough alignable with the surface. The purpose of the canopy is to vacuum solvent and entrained contaminant from the print head surface. Moreover, a piping circuit is provided for filtering the particulate matter from the solvent and for recirculating clean solvent to the surface of the print head.
In addition, a translation mechanism is connected to the hood, the wiper and the canopy for translating the hood, the wiper and the canopy across the print head surface. In this regard, the translation mechanism may comprise a lead-screw threadably engaging the hood, the wiper and/or the canopy. Moreover, a displacement mechanism is connected to the hood, the wiper and the canopy for displacing the hood, the wiper and the canopy to a position proximate the surface of the print head to enable cleaning of the ink channels and the surface of the print head.
A feature of the present invention is the provision of a cleaning mechanism associated with the print head, which cleaning mechanism is adapted to simultaneously clean contaminant from the print head surface and ink channels.
An advantage of the present invention is that cleaning time is reduced because the print head surface and ink channels are cleaned simultaneously.
These and other objects, features and advantages of the present invention will become apparent to those skilled in the art upon a reading of the following detailed description when taken in conjunction with the drawings wherein there are shown and described illustrative embodiments of the invention.